As part of the study of the structure and function of bovine rhodopsin it is desired to isolate large peptides from rhodopsin and place them in order in the primary sequence. Various functional groups such as phosphorylation site(s), cysteine residues, carbohydrate groups, are to be localized in specific peptides. The time course of the phosphorylation reaction is to be studied with regard to extent of phosphate incorporation and site specificity. Proteolytic digestion of rhodopsin in intact disk membranes will be used as a probe to study rhodopsin domains and any changes which occur upon bleaching. This year, some efforts were directed toward each of the above goals.